My philosophy of learning: The most important skills of the artist and naturalist are sustained attention and observation.  Technical skills will improve with regular practice, experimentation will reveal both your artistic and journaling preferences.  The biggest barrier to both is managing your feelings about your results.  If you can learn to accept and love the skills you already have as enough and keep going, you will improve and find joy and satisfaction in your journal. These are skills that are transferable in many other areas of life.